Floating loading hose

ABSTRACT

Device for storage or mooring of a loading hose ( 1 ), preferably for unloading of petroleum fluids from a vessel ( 100 ) at sea, with a floating loading hose ( 1 ) with the first end ( 1   a ) connected to an after manifold ( 6 ) of the vessel ( 100 ), with the second, free end ( 1   b ) of the loading hose ( 1 ) arranged to be caught and connected preferably to a midship manifold ( 7 ) of an other vessel ( 200 ). (a) A swivel ( 8 ) arranged for permanent pivotable connection between the first end ( 1   a ) of the loading hose ( 1 ) and the after manifold ( 6 ). (b) Hoisting appliances ( 9 ) with movable catch hooks ( 14 ) adapted to the loading hose ( 1 ) and arranged with mutual separation along the hull&#39;s side ( 102 ) forward from the after manifold ( 6 ) and arranged for complete or partial elevation of the loading hose ( 1 ) from the natural floating position.

This invention relates to a device for load transfer, particularlytransfer of petroleum fluids, between two vessels at sea, comprising atleast a loading hose arranged to be drawn between an after manifold atthe stern of a first vessel and a midship manifold at a second vessel.

This invention particularly relates to a device for mooring and storageof a normally floating loading hose when the loading hose is not usedfor transfer of petroleum fluids from a vessel at sea, preferably afloating (production,) storage and off-loading vessel FSO/FPSO.

Load transfer between to vessel units at sea is an especially demandingtask, particularly due to persisting relative movement between thevessels. A known method to perform this kind of operation is to arrangethe vessels in a tandem, that is, the second vessel moored from the bowparty to the stern of the first vessel. Typically this may be aso-called FPSO (Floating Production, Storage and Off-loading), while theother may be a tank vessel, particularly known as a shuttle tanker. Afloating loading hose may be used for the transfer, i.e. the dischargingor unloading from the FPSO and the loading of the shuttle tanker,whereas such a loading hose is constructed or arranged to float at thesea surface and to be towed on board to the shuttle tanker before loadtransfer. Modern shuttle tankers may have a bow manifold for charging,but a major proportion of the conventional shuttle tankers usually havea charging device consisting of a midship manifold for intake of the oilload. For this reason a relatively long loading hose is needed, from thestern on the FSO/FPSO-vessel to the midship manifold on the shuttletanker. The separation between the vessels, i.e. between the stern ofthe FPSO-vessel and the bow of the shuttle tanker may be about 50 to 90meters, and the extension of the loading hose is normally between 150and 300 meters. The internal diameter of the loading hose will normallybe between 10 and 20 inches, i.e. between 25 and 50 cm, adapted to theactual pumping rate for the oil charge. Conventionally the bullnose endof the loading hose is brought to the shuttle tanker by means of adedicated auxiliary craft, e.g. a tender.

Obviously such loading hoses floating freely in the sea in the periodsbetween load transfer operations, may be subject to wear and by thatrisk damage, both to the loading hose and its connection with thevessel, whether the weather conditions are difficult or not, butparticularly due to wave action. Under the present conventional storagemethod where the loading hose is drifting with the weather, hangingastern from the FPSO-vessel (which also may be lying on the weather,preferably single point moored, freely rotatable on a turret) theexperience has shown that the loading hose is worn due to wave action,gradually leading to loss of the buoyancy and beginning to sink, or thatit is torn off and lost. This of course implies a considerable expenseand a time loss, leading to delays and extra work beingdisproportionally expensive because of extraordinary operation out ofthe schedule, remotely at sea and often under heavy weather, with theproblems imposed by such a replacement both with respect to logisticsand with respect to working conditions, both of which relates to safety.Keeping a shuttle tanker lying waiting also leads to loss of money.

By a conventional method according to the above, where a mostlyconventional tank vessel shall receive a fluid load from an FPSO, aloading hose is laid out astern from the FPSO-vessel and along thehull's side of the tanker vessel for coupling to a midship manifold orthe like, which is normally situated about midship of the tanker vessel.When the shuttle tanker leaves the FPSO-vessel after the end of loading,the bullhead of the loading hose is dropped to the sea.

On the background of the above mentioned known art the inventioncomprises a device for arrangement of the loading hose during the timesbetween the load transfer operations. The new and characteristic traitsare primarily comprised of a hose swivel arranged for permanentswivelled connection between one of the ends of the loading hose and anafter manifold, and also mutually separated hoisting appliances withmovable catch hooks adapted for the loading hose, and arranged from theafter manifold forward along the hull's side, adapted to complete orpartial hoisting of the loading hose from the natural floating position.

Thus one achieves a device that gives a safe mooring possibility withthe loading hose pivoted in a forward direction about a hose swivel onthe after manifold and laid towards the hull's side of the FPSO-vesselor the FSO-vessel. When the loading hose is laid parallel with thehull's side, it may be engaged by the catch hooks of the hoistingappliances along the hull's side. The loading hose may then be hoistedcompletely or partially from the sea and thus become less exposed towaves and current with the inherent wear and damage of which the loadinghose otherwise would have been subject to if it were freely floating inthe sea.

Among the achieved advantages by such a solution we here mention asubstantially prolonged lifetime for the loading hose, less maintenancework, improved reliability for commencing the load transfer on schedule,reduced delay for shuttle tankers due to a defect loading hose, improvedsafety for vessels operating astern of the FPSO-vessel because noloading hose is drifting in the sea during intervals between loadtransfer operation times. If improved reliability for load transfer fromthe FPSO-vessel to the shuttle tankers is achieved, one may be able tokeep a more even and higher production of oil from the reservoir.

The favourable mooring conditions achieved for the loading hoseobviously depend on the number of hoisting appliances, their location onthe deck and their mutual separation, the design of the catch hookdevices and how high out of the sea one may, or wish, to hoist theloading hose. Clearly, under fair weather conditions it may suffice onlyto engage the catching devices to the loading hose, and hoisting it onlypartially up from the sea. On the contrary, it may, during heavy weatheror -wave conditions, be necessary to hoist the loading hose completelyup and above the sea in order to avoid damage on, or loss of, theloading hose.

As will emerge from the following, it may for certain conditions andoperations, be safeguarded considerable additional advantages by using awinch or hoisting crane arranged leading in the direction of the bowwith respect to the leading crane, and arranged to winch and tighten upthe loading hose by means of a hauling line attached near the free(bullnose) end of the loading hose.

The solutions comprised by the invention may be adapted for severalmodes of operation, such as:

An essentially stationary vessel of the FSO or FPSO type in harshweather areas, possibly also in less demanding weather areas.

The load to be transferred is oil.

Transfer of the oil and return of gas (VOC—Volatile Organic Compounds).

As for this, it must be mentioned that particularly during the waitinginterval between the previously described known tandem operations ofload transfer between two vessels under weather conditions or situationsas mentioned in the previous chapter, the known holding position andimperfect mooring methods often implies considerable risks as for wear,sinking and average of the loading hose.

Such unwanted incidences will, by means of the device according to theinvention, be substantially eliminated by ensuring that the loading hoseis hoisted or lifted mostly out of the sea during periods when it is notused for load transfer. The pivoting turning to the forward pointingdirection can be performed by means of lines or wires drawn between theFPSO-vessel and the loading hose, but in a preferred embodiment of theinvention be performed by means of an auxiliary craft or tender. It isalso possible to bring the loading hose towards the FPSO hull's side byrotating it by means of the FPSO-vessel's own engine force.

The invention will be explained in more detail in the followingchapters. The invention will be explained with reference to embodimentsthat are illustrated in the following figures:

FIG. 1a shows a plane view of the FPSO-vessel with a device according tothe invention in a moored position in the period between load transferoperations, and

FIG. 1b shows, in an elevation view from the port side, the FPSO-vesselwith the loading hose lying in a partially hoisted position from thesea, along the hull.

FIG. 2a shows, a vertical section along A-A′ from FIG. 1a, a hoistingdevice placed in an engagement position on the loading hose.

FIG. 2b shows a vertical section along A-A′ from FIG. 1a, a hoistingappliance with the loading hose in a hoisted position from the sea.

FIG. 2c illustrates two mutually orthogonal elevational section views ofthe catch hook for the loading hose.

FIG. 3 shows the vessels in tandem for load transfer.

Referring to the drawings, FIG. 1a shows a first vessel 100 (typicallyan FSO or an FPSO) with a loading hose 1 in the storage or mooringposition along the hull's side 102. Along the hull's side 102 hoistingappliances 9 are arranged, with even separation, forward from the aftermanifold 6. The loading hose is in the one end 1 a connected to theafter manifold 6 via an interconnected hose swivel 8. The opposite freeend 1 b of the loading hose 1 has a bullnose 12 arranged for loadtransfer connection to preferably a midship manifold 7 on an othervessel 200 (not shown) e.g. a shuttle tanker. The free end 1 b has in apreferred embodiment a hauling line 10 on a winch or crane 11 beingarranged closer to the bow 101 than the leading hoisting appliance 9.The hauling line 10 is arranged to tighten up the loading hose by meansof the winch or crane 11 when the loading hose is hoisted by means ofthe hoisting appliances 9, or put in the moored position along thehull's side 102. In this way the free end 1 b and the bullhead 12 issecured from swinging freely to be damaged toward the hull's side 102,and that the loading hose 1 is tightened up lengthwise so that theloading hose's freedom to swing sideward is reduced. This facilitatessimpler access to maintain the bullnose 12. This also gives thearrangement of the loading hose 1 stored along the hull's side 102 ofthe vessel 100 the possibility to connect the free end 1 b (the“bullnose”) of the loading hose 1 to the to the tube system of theFPSO/FSO-vessel 100 and gives the possibility to empty the loading hose1 for oil by pumping in e.g. water from the other end 1 a of the loadinghose 1. Environmentally this gives another advantage by eliminatingpollution by oil release when a loading hose goes average. The hoistingappliance 9 comprises in a preferred embodiment each their boom 9 bbeing adjustable in their horizontal extent from the hull's side 102,with wires 16 arranged to keep the catch device or catch hook 14 in anadjustable vertical elevation hanging from the end of the boom 9 b, asshown in the FIGS. 2a and 2 b.

FIG. 2a shows in a section A-A′ in FIG. 1 how the loading hose 1 can besituated when arranged in the sea along the hull's side 102 by theFPSO-vessel. The catch hooks 14 are here arranged engaging the loadinghose 1. The horizontal movement of the catch hooks 14 toward the loadinghose 1 may be effected by horizontal adjustment of the booms 9 b on thehoisting appliances 9, or effected by sideward directed force of thepropulsive power of the FPSO-vessel 100, either by means of thrusters 13or by means of the main propeller and the rudder. The loading hose mayalso be handled into an engagement position toward the catch hooks 14 bymeans of a tender (not shown).

FIG. 1b displays how the vessel 100 in a preferred embodiment of theinvention has at least two, preferably three or more hoisting appliances9 arranged mainly near the vessel's 100 after 103, midship, and near thebow 101. Depending on the bending capability and tensile strength of theloading hose 1, more than three hoisting appliances 9 may be arrangedalong the hull's side 102. In a preferred embodiment each catch hook's14 arc of contact 140 is arranged as a doubly curved saddle giving anarc of contact arranged to give an even bearing load force on the lowerside of the stored loading hose. It must be emphasized that the catchorgans or catch hooks 14 has a shape being rounded and adapted to thehose, preferably with a doubly curved (saddle) shape, arranged to engageand hold the loading hose in a doubly curved concave-convex arc ofcontact track which along an axis of the loading hose has a bendingradius somewhat 1 a rger than the loading hose, and which about anathwart axis has a bending radius 1 a rger than the minimum allowedbending radius of the loading hose, such that the loading hose is heldstably sideward and not bent past its allowed bending radius. Suchsparing catch hooks 14 adapted for flexible hoses ar described in theknown art, and are illustrated in FIG. 2c.

FIG. 3 shows vessels 100 and 200 in tandem under transfer of oil via theloading hose 1. The shuttle tanker's bow 201 is moored to the after 103of the FPSO-vessel by means of a bow hawser 2. In a preferred embodimentof the invention VOC-gas may be returned from the vessel 200 to the mainvessel 100. This return goes from a bow manifold 217 via a return hose17 a. The return hose 17 a may be stored on a drum 17 when not used in aloading operation. The loading hose 1 is taken on board by the side ofthe hull 202 and connected via the bullnose 12 to a midship manifold 7of the shuttle tanker 200. The shuttle tanker may be assisted by anauxiliary vessel (not shown) to keep a correct position with respect tothe FPSO-vessel 100.

The embodiment of the swivel 8, as such, is a task for the skilledperson when regarding the known art.

What is claimed is:
 1. A system for storing a loading hose for transferof petroleum fluids from a leading vessel at sea, in which said loadinghose is intended to be transferred from an inactive position where saidloading hose is stored above sea level to an active position,substantially floating on the sea level, for transfer of said petroleumfluids, said loading hose having a first end connected to an aftermanifold located on said leading vessel and a free end arranged to beconnected to a midship manifold of a trailing vessel, the systemcomprising: said loading hose, when in said inactive position havingsaid free end pointing forwardly in a longitudinal direction of saidleading vessel, while pointing aft when in said active position,connected to said trailing vessel; said loading hose in said inactiveposition are arranged for being stored along a side of the hull of saidleading vessel, suspended from a plurality of hoisting appliancesarranged along said side of said hull; a hose-swivel arranged forpermanent rotatable connection between said first end of said loadinghose and said after manifold, enabling said loading hose to be swungfrom said inactive position to said active position or vice versa; andsaid plurality of hoisting appliances having movable catching hooksadapted to receive said loading hose, said hoisting appliances beinggenerally equally spaced along a side of said hull of said leadingvessel extending forward from said manifold, and being adapted forcomplete or partial hoisting of said loading hose from a naturalfloating position.
 2. The system of claim 1, wherein each hoistingappliance comprises a boom adjustable in the horizontal direction fromsaid side of the hull; and a wire arranged to hold said catching hook,said wire hanging from an outer end of said boom and configured to beadjustable to raise and lower said hook.
 3. The system according toclaim 1, further comprising a winch positioned closer to the bow of saidleading vessel than each of said hoisting appliances, and arranged tohaul in a hauling line attached said free end of said loading hose. 4.The system according to claim 1, wherein the system includes hoistingappliances positioned adjacent to the stem, bow and midship of saidleading vessel.
 5. The system according to claim 1, wherein each of saidhooks comprise a contact surface for receiving said loading hose andwherein said contact surface has a doubly curved saddle for providing aneven bearing load force on a lower side of said loading hose.
 6. Amethod for storing a floating hose for transfer of petroleum fluids froma leading vessel at sea to a trailing vessel, in which said loading hoseis intended to be transferred from an inactive position where theloading hose is stored above the sea level to an active position,substantially floating on the sea level, for transfer of said petroleumfluids, the loading hose having a first end connected to an aftermanifold located on said leading vessel and a free end arranged to beconnected to a midship manifold of a trailing vessel, the systemcomprising alongside a leading vessel at sea comprising the steps of:providing said loading hose floating on the sea surface and having itsfirst end connected with an after manifold on said leading vessel, saidloading hose having a free end configured for connection to a midshipmanifold of another, trailing vessel; pivoting said loading hose aboutits said first end from a rearwardly directed position forward to amooring position along a side of the hull of said leading vessel;providing hoisting appliances having movable catching hooks, saidappliances being arranged with mutual separation along said side of thehull of said leading vessel; engaging said loading hose with saidcatching hooks; elevating said loading hose above a natural floatingposition for storage along said side of the hull.
 7. The method of claim6, further comprising the steps of: attaching a hauling line to saidloading hose's said free end using a winch arranged at the opposite endof said leading vessel with respect to said after manifold; and haulingin said free end of said loading hose; and securing said free end tosaid leading vessel.
 8. The method of claim 6, wherein each of saidhoisting appliance includes a boom, and said catching hook hangs from awire positioned at an outer end of said boom, wherein said step of saidloading hose with said catching hooks comprises the steps of: loweringsaid catching hooks down to the elevation of said hose; and adjustingthe position of said outer end of said boom re 1 a to said leadingvessel.